RTF malware analysis — malicious · ffa639560a2a0b31

MALICIOUS

RTF

461.0 KB First seen: 2021-06-13

MD5: 5993321a8b6c94b43119d05bdc136474 SHA-1: f367858b359556e229a8935cc12f607e9bf4e1ef SHA-256: ffa639560a2a0b31632918b6bdf24bd2449a96e3a168e7f3ba3b3feeaaafab90

280 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple OLE objects, including composite monikers, and triggers ".objupdate" which are indicative of exploitation attempts. Specifically, the CVE-2017-8570 heuristic indicates the file is designed to drop and execute a script. The embedded artifact objdata_01_off0000735b.bin is flagged as a suspicious extracted artifact containing shellcode command strings.

Heuristics 8

Composite Moniker — CVE-2017-8570 (drops SCT script) critical CVE related CVE_2017_8570

RTF \objdata decodes to OLE data containing the Composite Moniker — CVE-2017-8570 (drops SCT script) CLSID — the vulnerable control/moniker is embedded directly in the document's object stream, the delivery shape of this exploit. RTF objects auto-render when Word opens the file.
Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED

RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
Automatically linked OLE object high RTF_OBJAUTLINK

RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
\objupdate forces OLE activation high RTF_OBJUPDATE

RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
OLE object data medium RTF_OBJDATA

RTF contains 4 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
Macro/content-enable lure medium SE_ENABLE_LURE

Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00000bac.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xBAC	121698 bytes
SHA-256: `347714a7aca7829c5eaa40925966fba205337b0307d50e312685c140e4cfee69`
`objdata_01_off0000735b.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x735B	121671 bytes
SHA-256: `809165a3ff80f7a575a221097c083eeef41d19293926f0f1ee4641c701c8040c`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): WScript.Shell"")")
`objdata_02_off00045090.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x45090	2632 bytes
SHA-256: `32e8e449cdc043249ce37c79c9eaf2af80a02cb8175718a8a0ce726d961b7d16`
`objdata_03_off00046633.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x46633	12297 bytes
SHA-256: `e8d4fe950caed6dcfde26f4b616825bbe11b93458425974b7d075167f675abf7`

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